IdentifyFeature() use via PyQGIS?

Question

Intent is to have two variables (QgsVectorLayer and feature.id() within said layer) as input for the Identify feature map tool in Qgis (2.6). Wondering if a feature can be selected programmatically (via PyQGIS) to be highlighted in mapCanvas()?

I have reached 'writers' block after the following:

    layerID,featureID = [i for i in layerAndFeatureIDs.split("_")] 
    layerRef = ftools_utils.getMapLayerByName(unicode(layerID)) 
    infoTool = QgsMapToolIdentifyFeature(self.iface.mapCanvas(),layerRef) 
    ...? 

Runs without error - but hopeful to find out if calling a specific feature within a designated layer is possible. Either by way of a feature.id(), or even the centroid of said feature as a QgsPoint reference.

---

This command might be relevant. It activates the tool in question, but is it possible after triggering to subsequently highlight or info-select programmatically?

        self.iface.actionIdentify().trigger()

---

I wondered if an alternative method would be to source the feature in questions centroid. Yet upon deriving such - and (futily?) implacing that location into a simulated click event on mapCanvas(); no results were had. Although, a print of 'working' did return...

    for feature in layerRef.getFeatures():
        if feature.id() != int(featureID):
           pass
        elif feature.id() == int(featureID):
           x,y = feature.geometry().centroid().asPoint()[0],feature.geometry().centroid().asPoint()[1]
    self.iface.setActiveLayer(layerRef)
    self.iface.actionIdentify().trigger()
    virtualMouseClick = QtGui.QMouseEvent(QtCore.QEvent.MouseButtonPress,QtCore.QPoint(x,y), \
                        QtCore.Qt.LeftButton,QtCore.Qt.LeftButton,QtCore.Qt.NoModifier)
    try:
        self.iface.mapCanvas().mousePressEvent(virtualMouseClick)
        print 'working'
    except:
        print 'not working'

---

After @sigeal's advice, I have given a go at implementing some things - but run into a bit of a problem. I am supposing that the sub-classed tool needs its x,y coordinates as pixel rather than map coordinate origin. Yet use of QgsMapToPixel returns '-inf' (negative infinity) values.

What might be the syntax error I am committing, and am I off target in actions on @sigeal's advice?

#-------From main class----------------------
    ...
    for feature in layerRef.getFeatures():
        if feature.id() != int(featureID):
            pass
        elif feature.id() == int(featureID):
            point = feature.geometry().centroid().asPoint()
            x,y = point[0],point[1]
            deviceX,deviceY = QgsMapToPixel().transform(float(x),float(y))[0],QgsMapToPixel().transform(float(x),float(y))[1]
            print deviceX,deviceY
    self.iface.setActiveLayer(layerRef)
    self.iface.actionIdentify().trigger()
    try:
        featureIdentifyTool(self.iface,layerRef,deviceX,deviceY)
        print 'working'
    except:
        print 'not working'

    ...

class featureIdentifyTool(QgsMapToolIdentifyFeature):
   geomIdentified = pyqtSignal(object, object)
   def __init__(self, iface, layer, x, y):
       QgsMapToolIdentify.__init__(self, iface.mapCanvas())
       self.canvasReleaseEvent(layer,x,y)
   def canvasReleaseEvent(self,layer,x,y):
       results = self.identify(x, y, self.ActiveLayer, [layer], self.VectorLayer)
       print results
       if len(results) > 0:
          self.geomIdentified.emit(results[0].mLayer, results[0].mFeature)

Answer 1

The custom featureDialog may do what you need. I use it extensively in my plugin Telemetry Layer: http://southweb.co.nz/telemetrylayer. It can be called with a layer and feature or respond to user clicks. There are some quirks with it though.

Answer 2

Just a hint : you can subclass QgsMapToolIdentifyFeature. This way you can override methods you need to customize :

class YourIdentifyTool(QgsMapToolIdentifyFeature):

    geomIdentified = pyqtSignal(object, object)

    def __init__(self, iface):

        # Parent constructor
        QgsMapToolIdentify.__init__(self, iface.mapCanvas())

    def canvasReleaseEvent(self, mouseEvent):

        results = self.identify(mouseEvent.x(), mouseEvent.y(), self.TopDownStopAtFirst, [self.arretLayer], self.VectorLayer)
        if len(results) > 0:
            self.geomIdentified.emit(results[0].mLayer, results[0].mFeature)

---

Actually I have only used this technique to define a custom identify tool that is intended to be used interactively. To do that, I connect the toolButton's clicked signal with a method which is run when the tool is activated (selected), and in that method I connect the tool's geomIdentified signal with the method I want to run when a feature is identified.

# toolButton's clicked signal connection
toolButton.clicked.connect(toolButtonSelect)

# Method run when toolButton is activated
def toolButtonSelect(self, checked):

    # If the toolButton is checked
    if checked:
        self.featIdentTool = FeatureIdentifyTool(self.iface)
        self.featIdentTool.geomIdentified.connect(self.toolButtonAction)
        self.iface.mapCanvas().setMapTool(self.featIdentTool)

# Method run when a feature in layer is identified by featIdentTool
def toolButtonAction(self, layer, feature):

    # Do something with identified feature
    if isinstance(layer, QgsVectorLayer) and isinstance(feature, QgsFeature):
        self.featIdentTool.doWhatEver(feature)

Now, I don't know how to trigger the geomdentified signal and send it xy coordinates... May be this link can help you : http://pyqt.sourceforge.net/Docs/PyQt4/new_style_signals_slots.html